This couldn't backfire, could it?... Cane toad edition

One of my favourite topics to write about (and to talk about in my ECONS102 class) is unintended consequences. There is a famous story about cobras that exemplifies the topic, as I wrote about in 2015:

The government was concerned about the number of snakes running wild (er... slithering wild) in the streets of Delhi. So, they struck on a plan to rid the city of snakes. By paying a bounty for every cobra killed, the ordinary people would kill the cobras and the rampant snakes would be less of a problem. And so it proved. Except, some enterprising locals realised that it was pretty dangerous to catch and kill wild cobras, and a lot safer and more profitable to simply breed their own cobras and kill their more docile ones to claim the bounty. Naturally, the government eventually became aware of this practice, and stopped paying the bounty. The local cobra breeders, now without a reason to keep their cobras, released them. Which made the problem of wild cobras even worse.

So, I was interested in this article in The Conversation last week by David Smerdon (University of Queensland), which references to cobra story, as well as this one about rats in Vietnam:

When the colonial government built a sewerage system under Hanoi early in the 20th century, it inadvertently helped create a rat plague. Its solution was a cash-for-rats scheme - though to save the government having to dispose of hundreds of thousands of rat carcasses, it only required collectors turning in a rat’s tail to claim their bounty...

The consequences this time were not only the creation of pop-up rat-breeding farms, but also hordes of tail-less rats roaming the city streets.

Seen from 2019 New Zealand, this story is hilarious. But, the point of Smerdon's article is this:

[Australian Senator Pauline] Hanson’s proposal involves paying welfare recipients 10 cents for each toad they collect (alive) and hand over to their local council. The council would then kill the toads humanely in large freezers.

The senator is right to be concerned about the cane toad problem. Introduced in the 1930s as a biological fix to control native beetles eating sugar cane crops, the animals have prospered with devastating impact on native flora and fauna. It’s estimated there are now more than 200 million across Queensland and northern New South Wales.

So, cane toads are almost a double example of unintended consequences, given the reason they were introduced into Australia in the first place! In any case, even though paying a bounty for cobras, rats, ragweed, possums, or cane toads sounds good in theory, surely we could learn the folly of this approach from historical examples?

Read more:

• This couldn't backfire, could it?... Possum bounty edition
• This couldn't backfire, could it?... Ragweed edition